linux/cmake: Allow libbacktrace to be disabled

[F0bes]

RFC? Should this be implemented?

Description of Changes

Adds the USE_BACKTRACE CMake build option to optionally disable libbacktrace

Rationale behind Changes

fixes #11566

Suggested Testing Steps

Try to build with -DUSE_BACKTRACE=1 (default) and -DUSE_BACKTRACE=0

Please know that support will not be given for builds with libbacktrace disabled.

I'd also like to remind Linux users: First class Linux support is provided for the AppImage and Flatpack only. If it is not reproducible on either builds, we will consider the issue invalid.